A glass rod is rubbed with silk. Explain the charging of the glass rod and the silk on the basis of electron movement.
A glass rod is rubbed with silk. Glass rod loses electrons and becomes positively charged.
Silk gains electrons and becomes negatively charged.
Explanation: Suppose glass rod in neutral form has 10 protons and 10 electrons
i.e. 10 units of positive charge
and 10 units of negative charge.
While silk has (in neutral state) 7 electrons and 7 protons i.e. 7 units of negative charge and 7 units of positive charge.
Suppose on rubbing together glass rod loses 2 electrons and silk gains 2 electrons.
Now glass rod has 8 electrons and 10 protons on it.
i.e. 8 units of negative charge and 10 units of positive charge i.e. glass rod has net 2 units of positive charge. Thus, the glass rod has acquired positive charge.
Silk has now 9 units of negative charge and 7 units of positive charge i.e. silk has net 2 units of negative charge. Thus, silk has acquired negative charge.